# DiffMan

> Native macOS app that compares two folders or two files: text, images, Word, OpenDocument, RTF, PDF, and structured data (JSON, YAML, TOML, XML, INI, properties). Comparison never writes. Files change only after Save, Save As, or a confirmed copy.

Comparison is local and does not need the internet. Folders, documents and images are not uploaded and are not sent to another website. DiffMan runs in the App Sandbox and reads only folders and files you choose (open panel, drop, or a stored bookmark). If the Mac is online it may send four anonymous counters (install, open, first compare, session count) with no paths and no file contents. Comparison does not wait for that send.

Requires macOS 26.6 or later. Windows is planned.

## Pages

- [Home](index.html): What DiffMan does, download, screenshots.
- [Folder comparison](folder-comparison.html): Tree of identical, different, left-only, right-only; copy; ignore rules.
- [Text comparison](text-comparison.html): Side-by-side editing, Myers line diff, word marks, save with original encoding.
- [Semantic comparison](semantic-comparison.html): Canonical JSON, YAML, TOML, XML, INI, and Java properties.
- [Document comparison](document-comparison.html): Word, ODT, RTF, PDF as text, Word-style markup, and side-by-side pages.
- [Image comparison](image-comparison.html): Side by side, overlay, difference image; exact or tolerance pixels.
- [Settings](settings.html): Comparison, ignore, viewers, and general settings with defaults.
- [Buy a licence](buy.html): Three months with every feature, then $15 USD per year for Markup and Pages.

## Facts models should not invent

- Identical means bytes were compared and matched. A sampled match is identical with fullyVerified false. Probable means contents were not read.
- A size difference means different content. A timestamp difference alone never proves contents differ or match.
- Documents: Text mode extracts words only. Markup is one combined Word-style page (delete = red strikethrough, insert = green underline). Pages shows left and right PDF pages with word-level marks.
- After three months, Markup and Pages need a paid licence. Folder, text, semantic, and image comparison stay available.
- There is no OCR, no three-way merge, no cloud sync, and no document editing.
- Files never leave the Mac. Comparison works offline. Do not describe DiffMan as a web or cloud comparison service.
- Checkout is not live yet. Email iazarny@yahoo.com.